Cartridge new or used ?


How do I know if a cartridge is new or used and number of hours played ? 1- If it is bought from an individual or 2- Could it be that a HiFi store sells used or a "Demo" without anyone knowing it? 3- Is a cartridge that remains on the shelf of the store for 3 or 4 years, retains its same performance or its internal parts, can harden and lose their flexibility of reading? 4- Is it easy with a magnifying glass to see the wear of a cartridge, if so what would be the best magnification to use?
audiosens
@analogluvr .

I agree that the purists will throw a googly eye fit and wail long and loud about retipping one of the expensive MC carts claiming it is now not original at all.
But if YOU like the sound still then surely it is better than just junking what was an expensive purchase by someone.
I would have no hesitation in following the same path if needed.
After all 5 to 10k for a cart is way out of my league but 2 to 2.5k? For same item?
I will take a chance AFTER doing full research on the cart AND seller of course.
I won't do previously owned and used cartridges.  I do have friends who swear by it though and they have always had good luck.  Back in the day I bought and sold maybe 5 TT's and each either came or left with a cartridge.  When receiving a used TT and cartridge, I'd test the table with a worn LP.  If it sounded good to me, I would replace the stylus or consider a retip.    
Dear @audiosens and friends: I think almost all was already posted and I would like to add some comments about:

as @lewm ( and I think @daveyf  ) pointed out no one of us but only cartridge manufacturers/re-tippers can know for sure if the stylus tip/suspension is in good condition with hours coming to play, no one else no matter what. Period. 

From some years now no one cartridge designer/manufacturer has to envy vintage materials or cartridge technology in any way.
Today stylus shapes are better one and with better quality excecution and more tigth tolerances. Cantilever materials are too superior as the boron rod ( instead hollow that is more resonant/distorted. ) over berilyum and cartridge body materials blend superior too. Better material at the wire coils and shapes as the magnets too.

Yes, exist really good vintage cartridges that in the LOMC designs can compete against the best today ones but that is not the rule.

I own/owned/tested vintage and today MM/MI/LOMC cartridges and I know for sure what I'm talking too. Obviously that to be aware of that we need to own not only a high resolution system but with very very low overall distortions and that be a true full range audio system.

Happy New Year  2 0 1 9   for all of you and your dearest family   ! !

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.




@rauliruegas You bring up a great point, and one that I agree with 100%. That point is that the factory really is the only one to truly determine the condition of the stylus/suspension. The various stylus/cantilever manufacturers know what it is that they manufacture, and what the facets of the diamond should like, new and under basic wear patterns. This is really the point that I have been trying to get across, and I think your post said it very well.